1. Field of the Invention
The present invention relates to an electronic musical instrument with a digital filter unit; more particularly, to an electronic musical instrument having a digital filter unit that computes a coefficient to be supplied to a digital filter.
2. Description of the Related Art
Recently, a digital filter unit is being used in electronic musical instruments, etc. to generate musical tones having various timbres.
The digital filter characteristic of the digital filter unit is determined by providing a predetermined filter coefficient from an external source.
Employing the above digital filter unit, an electronic musical instrument uses the above digital filter to control the timbre of tone signals. More specifically, tone signals with various timbres are generated by dynamically changing filter coefficients which are supplied to the digital filter unit.
Conventionally, to dynamically change filter coefficients to the digital filter unit, multiple predetermined filter coefficients are stored in a memory, and a controller reads desired filter coefficients from the memory, and supplies them to the digital filter unit.
To provide a digital filter unit that has various filter characteristics, however, filter coefficients to determine various filter characteristics must be stored in a memory in advance. This requires an excessively large memory storage capacity.